Why should you consider pulp protection and what are functions of the pulp?
Wish to maintain vitality of pulp:
- formative: produces dentine and odontoblasts
- nutritive: nourishes avascular dentine, non vital teeth are brittle
- protective: carries nerves that give dentine sensitivity
- reparative: produces new dentine in relation to physiological wear and unexpected insult such as caries
Name some sources of chemical attack on the pulp:
- acrylic resin in polymeric materials
- acids in certain dentine bonding agents
- residual acid from acidogenic bacteria
What are the constituents of the smear layer?
- bacteria from cavity
- collagen
- hydroxyapatite crystals
What are the properties of calcium hydroxide e.g. dycal?
- high pH gives beneficial irritancy
- high pH renders it bactericidal
- thermal and electrical insulator
- radiopaque
- good restorative material compatibility
- insufficient strength to withstand amalgam condensation
- not adhesive so no coronal seal
What are the properties of poly-f?
Polycarboxylate cements:
- acidic but high molecular weight reduces penetration and so mildly irritant to pulp
- fluoride renders them bacteriostatic
- thermal and electrical insulator
- strength for amalgam packing
- adhesive so coronal seal
- not obtundant to pulp
What are the properties of zinc oxide eugenol? e.g. Kalzinol
- beneficial irritancy
- bactericidal due to zinc
- thermal and electrical insulator
- resin reinforcement withstands condensation
- radiopaque due to zinc
- obtundant
- incompatible with resin composites, impairing polymerisation, affecting bond strength
- non adhesive so no coronal seal
What are the properties of glass polyalkenoates? e.g. vitrebond
- high molecular weight parent acid renders them mildy irritant
- bacteriostatic due to fluoride release
- thermal and electrical insulator
- strength to withstand restoration placement
- adhesive
What pulp protection should you use?
Cavities 2mm or less - no lining required
Cavities significantly deep - within 0.5mm of pulp: hard setting CaOH (do not need to cover with RMGIC unless restoring with amalgam)
Where should you use linings?
- pulpo-axial wall
- occlusal floor
- any areas directly overlying the pulp
What is an indirect pulp cap?
- when cavity extended to within 0.5mm of pulp
- CaOH hard setting is applied to deepest part of cavity
- restored as normal
What is a direct pulp cap?
- when an exposed pulp is covered by a capping material
- usually hard setting calcium hydroxide or mineral trioxide aggregate (MTA)
What is the criteria for direct pulp capping?
- tooth is vital
- no history of pain in the tooth
- no evidence of peri-radicular pathology
- pulp pink and healthy, no excessive bleeding
If any of the above are true, probably requires RCT or XLA
What is stepwise excavation?
- technique used in the management of deep carious lesions to avoid pulp exposure and thus reduce risk of pulp pathosis
- partial caries removal employed
- caries overlying pulp left in situ
- cavity dressed and revisited later
- avoid unnecessary pulp exposure
What is the rationale for stepwise excavation?
- caries can arrest if substrate is removed
- seal off lesion from mouth to allow to arrest
- pulp exposure avoided by allowing time for new dentine to be laid down and for lesion to arrest
What are some indications of a stepwise approach?
- deep carious lesion approaching pulp
- pulp exposure likely if complete caries removal attempted
- pt good attender and motivated
- no history of pain suggestive of irreversible pulpitis
- positive vitality established
- no peri-radicular pathology
- tooth not TTP
What is the stepwise excavation technique?
- LA, access lesion and begin caries removal as normal
- clear the ADJ/margins of all carious tooth tissue
- soft leathery wet caries on pulpal floor/pulpo-axial wall left alone
- dress the tooth with a material that gives a good coronal seal e.g. GI or RMGI
- remove all of the dressing at least 12 months later and review cavity
What is the aim of stepwise after removing the dressing?
- cavity floor should now be stained but no longer soft - now firm
- lesion arrested and pulp vitality maintained
- tooth can now be restored with a permanent material
- if soft dentine still present, consider repeating stepwise ? good coronal seal
